102 GRASSliS OF IOWA. 



of grasses have been a commercial article for a much shorter 

 period of time than have the seeds of most of our field and gar- 

 den crops. Grasses were long regarded as one of nature's 

 gifts, like air and water, and as little effort was made to 

 improve their quantity or quality; little attention was paid 

 to their seeds until recent years when various causes have 

 combined to place hay and pasturage among the most impor- 

 tant of our farm products. At the present time only imperfect 

 devices exist for gathering and cleaning the seed, and little is 

 known as to the best methods for increasing and retaining the 

 vitality. In order to secure the greatest quantity at the least 

 expense the seeds of many species are gathered while still 

 green, and in this way the vitality is doubtless imp tired. The 

 drying of such green seeds is often imperfectly done and many 

 of the seeds become mouldy. 



The demand for the se ds of any but the most common 

 kinds is so very limited and irregular that they may be held 

 over from year to year in ihe unsold stock of the seedsman until 

 their vitality is almost or completely exhausted. 



In many of the grasses, as the blue grasses (Poa species), 

 fescues (Pestuca species), ray grasses (Lolium species), orchard 

 grass {Dactylis glomerata), and others, the seed as gathered con- 

 sists of not only the grain or caryopsis itself but also of the 

 flowering glume or chaff which surrounds the seed more or less 

 closely. This fact often makes it very difficult to say whether 

 what appears to be a seed actually contains a seed or whether 

 it is only an empty chaff. This can be determined only by a 

 careful examination. Where this emp^y chaff made up a large 

 per cent of the total it is evident that the vitality of the sup- 

 posed seed would be very low. 



Table No. V gives the average percentages of purity and vital- 

 ity possessed by choice grass seeds. The figures were obtained 

 from an extensive series of microscopic examinations and 

 germination tests and were compiled by Prof. Gerald McCarthy 

 from his own work* at the North Carolina Experiment Station, 

 from the reports of many other American stations and four of 

 the leading European seed stations, and from data furnished 

 by many American and foreign seedsmen. The last three 

 columns give the maximum, minimum, and optimum tempera- 

 tures for germinating these seeds. 



♦Bull. N. C. Agr. Exp. Station. 108: 383-384. 1894. 



